On the Creep Strength-Rupture Ductility Behaviour of 1.25Cr-0.5Mo Low Alloy Steel


Abstract: It is important to select materials having both high strength and good ductility in most engineering applications. This is also true for high temperature problems and the requirement of high creep strength as well as high rupture ductility is of prime concern. The creep data of ferritic low alloy 1.25Cr-0.5Mo steel, which is extensively used in piping systems of fossil power plants, has shown loss of rupture ductility after certain exposure time depending on its initial microstructure and applied stress. This unexpected loss of ductility is called as rupture ductility trough, and this study covers the attempts to investigate the dependency of creep rupture ductility of 1.25Cr-0.5Mo steel on microstructure and stress, in the temperature range of 773-923 K. An empirical relationship in exponential character was developed to predict the rupture time leading to rupture ductility trough, depending on temperature and the initial structure of steel. Finally, a rupture ductility map was constructed for each steel investigated in this study, in order to present rupture strength-rupture ductility data in a more appropriate way.

Keywords: Low Alloy Ferritic Steel, Rupture Ductility, Creep Strength, Rupture Ductility Trough, Rupture Ductility Map

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